How to Cross-Pollinate Grape Vines

Provide a sturdy support system for grape vines.

The three main varieties of grapes include muscadine, European and American. Muscadine grape vines are either male or female and need cross-pollination to mature into fruit. European and American have both male and female parts on each flower and self-pollinate themselves. You may cross-pollinate grape vines to make a new hybrid between two types of grapes or to ensure good pollination and more fruit in each cluster of like varieties.

1

Observe the flower clusters on each grapevine to determine if they are male, female or perfect. Male flowers have stamens, which are small filaments with anthers containing the pollen on the ends. Female flowers appear the same but have ovaries and stigmas that are a large green pod underneath the stamens and a thin, green point in the center of the blooms. Perfect flowers are both male and female. They contain stamens, ovaries and stigmas, but the large pod is above the bloom.

2

Snip a flowering cluster off a male grape vine with pruning shears. Lay the cluster on a sheet of paper and allow it to dry for two days.

3

Emasculate the female cluster if there is a tiny cap, or calyptra, on the end of each bloom. Use a pair of small forceps to pull the caps off the ends to allow the fibers of each flower to be free of the cap. If the caps have already fallen off, skip this step.

4

Place a small paper bag over each female flower cluster. Tie a string around the bag onto the vine to keep it in place; this action also protects the female flower from pollination by another male grape. Wait two to four days for the female flowers to mature and reach their peak time of receptivity; the fibers underneath each cap will appear feathery when the female bloom is ready.

5

Pick up and shake the male flower cluster over the sheet of paper to remove the pollen. Fold the paper in half and tap it to direct the pollen to the fold. Pour the pollen into an open a vial.

6

Wash your hands and a small soft paintbrush in 70 percent ethanol to disinfect your hands and the paintbrush for better results in pollination. Let the paintbrush air dry thoroughly.

7

Remove the paper bag from the female flowers. Dip the paintbrush in the vial and touch the pollen to each bloom on the female cluster. Replace the paper bag on the female blooms to identify which blooms received the procedure of cross-pollination between two varieties. If your cross-pollination was between male and female grapes of the same type, you do not need a bag over the flowers to identify them.

Things You Will Need

Pruning shears

Sheet of paper

Glass vial

Small forceps

Paper bag

String

70% ethanol

Small soft paintbrush

Tip

The technique of bagging grapes keeps them safe from foraging birds and fungal disease. Grape vine leaves need sunlight to transfer the sugar content to the grapes, but the fruits do not need sunlight to grow.

If the female caps are off the flowers and the male flowers are blooming at the same time, you can clip off a male bloom and tap it on the female flowers to cross-pollinate the two.

Warning

Clean your hands and paintbrush with ethanol before each cross-pollination to disinfect them and protect the blooms from germs or diseases.